As is known, increasing demand exists for memories characterized by flexibility, low power consumption and immunity to noise. These characteristics are extremely difficult to achieve simultaneously, because in known devices, each can only be obtained at the expense of the others. As such, a trade-off is inevitable, bearing in mind the effect in terms of technological yield, and the impossibility of achieving an all-around solution suitable for all applications.
A timer, for example, is useful in reducing power consumption but, being invariably rigid, responds poorly to certain inevitable technological changes that are better catered to by a static-type architecture.
Moreover, a timed architecture, though it provides for solving certain noise, dissipation and speed problems, is limited in situations where certain lines are slowly brought up to the steady-state condition.
Bearing in mind these and many other factors (e.g. slow memory locations, shifts in component characteristics, and localized nonuniform behavior), a timer has been proposed for regulating the duration of the load pulse according to the characteristics of the memory. This architecture provides for exploiting the advantages of the timed approach (low consumption, speed) while at the same time recovering slower devices, or devices with nontypical parameters or involving frequent resetting of lines which are slow to reach the correct steady-state level.
On the other hand, to obtain a good degree of immunity to noise when loading data into the output circuits requires the generation of load pulses of as short a duration as possible. One way of doing this is by maintaining the output circuits disconnected from the internal memory circuits, and only permitting a very brief connection when actually loading the data. Noise immunity as described above, however, depends entirely on the load pulse being very short, and is lost or at any rate considerably reduced in the event the duration of the load pulses is extended for recovering slower devices and situations.